The laboratory diagnosis of platelet disorders

To provide both a detailed description of the laboratory tests available in the diagnosis of platelet disorders and a testing algorithm, based on platelet count, that can be used to direct the evaluation of platelet disorders.

A literature search was conducted using the National Library of Medicine database.

The literature on laboratory testing of platelet function was reviewed.

Based on the literature review, an algorithm for platelet testing was developed.

A history of mucocutaneous bleeding often indicates abnormal platelet function that can be associated with a normal, increased, or decreased platelet count. Multiple laboratory procedures can now be used to determine the underlying pathologic condition of platelet dysfunction when other deficiencies or defects of the coagulation cascade or fibrinolysis are ruled out. Simple procedures, such as platelet count, peripheral blood smear, and a platelet function screening test, will often lead the investigator to more specific analyses. Although platelet function testing is often limited to larger medical centers with highly trained technologists, newer technologies are being developed to simplify current procedures and make platelet function testing more accessible. This review provides an algorithm for platelet testing that may be of benefit to pathologists and physicians who deal with hemostatic disorders.